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Patterns of inheritance Flashcards

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1
Q

name the two types of speciation?

A

allopatric
sympatric

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2
Q

define allopatric speciation?

A

form new species from geographical isolation

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3
Q

define sympatric speciation?

A

when population diverges into two species within the SAME geographical area due to reproduction isolation

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4
Q

why does allopatric speciation occur?

A

because the populations separated experience different selection pressures

this causes reproduction isolation so there is no gene flow so a new species is formed on each island for example

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5
Q

describe the 5 steps of sympatric speciation?

A
  1. genetic variation due to random mutation
  2. niche developed as one mutation gives individual trait to occupy a different niche
  3. natural selection , traits more likely to survive and reproduce
  4. genes flow between subpopulations
  5. reproductive isolation to genetic differences
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6
Q

name 3 environmental selection pressures experienced by animals

A

predation
competition
disease

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7
Q

what is a codominance cross
is it monohybrid or dihybrid ?
what ratio does it present and why?

A

monohybrid
1:2:1 because both visual characteristics from parents are shown

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8
Q

what does a dihbyrid cross show about the characteristics , one or two being shown?

A

2 characteristics at the same time

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9
Q

when pure breeding what cross does this always present?
mono or dihybrid cross?

A

monohydrid

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10
Q

whats a real life example of codmoniance?

A

blood groups as multiple alleles but group 0 has no genotype

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11
Q

for heterozygous dihybrid crosses what is the ratio?

A

9:3:3:1

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12
Q

define genetic drift?

A

random changes in allele frequencies in population occurred by chance

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13
Q

does genetic drift happen over time or in short periods of time?
why?
give an example?

A

changes happen over time due to no selection pressures
ie: failed to locate a mate or killed in rock fall

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14
Q

for allele frequencies does a small gene pool or a large gene pool have the most pronounced affect with population size?

A

small gene pool will have most profound effect

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15
Q

what is the founder affect?

A

occurs when new population formed from few original founders
they carry only a small fraction of total genetic variation of parent variation

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16
Q

within the founder affected , do the founders carry a small or large fraction of total genetic variation?

A

small fraction

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17
Q

what representation of alleles does the founders have on the new island they have founded?

A

contain small representative sample of alleles

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18
Q

why may a allele be lost in the founder affect?
what will happen over generations?

A

allele lost due to individuals failing to mate and produce offspring

over generations mutation will occur producing new alleles which then become more common

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19
Q

what does the hardy Weinberg equilibrium equation demonstrate?
whats it used for?

A

see if the population is undergoing evolutionary change or is stable

used to estimate allele and genotype frequencies in genotype

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20
Q

in order to determine if the population is undergoing evolutionary change, what must the population have NONE off to use the hardy Weinberg?

A

no selection pressures
no mutations
no migration
needs a large population
needs random mating

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21
Q

within the hardy Weinberg calculation what does p present?

A

frequency of dominant alleles

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22
Q

within the hardy Weinberg calculation what does q represent?

A

recessive allele frequency

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23
Q

what is the chi squared equation used for?

A

test whether there is significance between observed and expected frequencies

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24
Q

when would you accept the null hypothesis?

A

if the x2 is LOWER than the critical value because any change is due to chance

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25
when would you reject the null hypothesis?
if x2 ABOVE critical value because caused by something other than chance
26
what would you say for your null hypothesis?
no significant difference between observed and expected frequencies because happened by chance
27
what does bottleneck cause? what is bottle neck caused by?
drastically changes sizes of population not caused by natural selection, rather by chance
28
what is an inbreeding depression?
little genetic diversity
29
whats the process of bottleneck?
1. natural disaster occurs 2. population reduced and loss of alleles 3. population then grows in a large size again but there is a lower genetic diversity
30
define a gene?
A length of DNA that codes for a single polypeptide or protein
31
whats a phenotype?
observable characteristics of an organism
32
what are the two linkages in genetics?
autosomal linkage sex linkage
33
out of men and women what sex is more likely to inherit a disorder?
men because the males don't have another X chromosome to compensate for a mutation on their x chromosome whereas for women they have 2 x so if one has a mutation the other one compensates for it so the women is only a carrier
34
what is autosomal linkage?
on the autosomes meaning any other chromosome other than a sex chromosome when independent assortment doesn't occur in meiosis so the genes are linked and stay together in the original parental combination Autosomal linkage refers to genes that are located on the same autosome and are inherited together more frequently than by chance. They tend to be inherited together—this is linkage.
35
phenotypic variation can be caused by environmental and genetic variation. what are examples for both?
environmental : difference in height when grown In different conditions genetic : four different blood groups
36
phenotypic variation can also be caused by both genetic and environmental, what is an example of being affected by both?
sickle cell anemia which is recessive determined by genotype and interaction of the environment
37
list some environmental factors that affect phenotype of organism?
length of sunlight hours supply of nutrients availability of water temperature range oxygen levels
38
can Variation in phenotype caused solely by environmental pressures or factors be inherited?
No cannot be inherited by offspring
39
what is etiolation?
when plants grow in darkness or cannot get access to magnesium so they become yellow even though genetically they should be green genetically should grow normally but instead may have long stems , small curled leaves this is due to their environment affecting their phenotype
40
define genetic variation?
small differences in DNA base sequences between individual organisms within a species
41
During sexualreproduction, genetic variation is transferred from one generation to the next, what does this cause?
phenotypic variation
42
state three things which cause phenotypic variation? (think of meiosis)
independent assortment crossing over random fusion of gametes during fertilisation between zygotes so each will have unique variation of alleles
43
if an individual has the genotype FFGG, what would it be with linkage?
FGFG
44
what would an unexpected ratio of 1:1 suggest?
linkage
45
when does epistasis occur?
occurs when two genes on different chromosomes affects the same feature
46
In a standard dihybrid cross between two double heterozygous parents we would expect to see a ratio of 9:3:3:1 in the offspring , what would the ratio be with epistasis for example?
9:3:4
47
'variation refers to the differences that exist between individuals of a species' what is this describing?
infraspecific variation
48
what is continuous variation?
is the differences between individuals of a species where the differences are quantitative (measurable)
49
what is discontinuous variation?
refers to the differences between individuals of a species where the differences are qualitative (categoric)
50
within continuous variation is there definitive characteristics ?
no there is no categories rather there is a range of values ie: mass or height of a human
51
list features of a continuous graph?
no distinct classes or categories characteristics can be measured and fall within a range between two extremes
52
for continuous variation is it dependent on environmental or genetic variation? or both?
BOTH
53
does discontinuous variation have distinct categories?
yes with no intermediates ie: blood group , there's 4 distinct categories a person can have only one of them
54
name the three features of a discontinuous graph?
1. distinct classes or categories exist 2. characteristics cannot be measured over a range 3. individuals cannot have features that fall between categories
55
for discontinuous variation is this caused by environmental or genetic variation? or both?
genetic because different genes have different effects on the phenotype
56
define selection pressures?
Environmental factors that affect the chance of survival of an organism
57
name the two types of selection? (selection pressures)
stabilising directional
58
what is stabilising selection?
natural selection keeps allele frequencies constant over generations things stay the same unless there is change in the environment
59
name an example of stabilising selection?
human birth weights very low and very high brith weights are selected against leading to maintenance of intermediate birth weights
60
what is directional selection?
natural selection that causes gradual change in allele frequencies over several generations usually happens when there is a change in environment or new allele appeared in the population
61
with directional selection, what happens over time to the alleles?
1. there is phenotypic variation with a population 2. and a selection pressure will favour some phenotypic variation more than others 3. phenotype produced by particular alleles 4. individuals with favoured alleles / phenotype reproduce and survive passing down the advantageous alleles 5. frequency of advantageous alleles increases
62
does natural selection have a moire profound effect on larger or smaller populations?
more profound effect on evolution of larger populations
63
how does evolution cause speciation?
because formation of new species due to change in gene pools
64
for speciation what is necessary for new population to occur?
gene isolation
65
what causes allopatric speciation to occur?
geographical isolation
66
whats the end result of allopatric speciation?
creates two populations of the same species who are reproductively separated from each other, and as a result, no genetic exchange can occur between them
67
within allopatric specification how is separate specifies formed? what has to occur?
selection pressure which causes gene pools to change so then the gene pools will diverge and form separate species over time the species may present to be different psychologically , behavioural structurally
68
what causes sympatric speciation?
no gene flow between two populations which is not caused by geographical barrier
69
name two splits that can happen in symaptric speciation which causes no gene flow?
ecological seperation (seperated because live in different environments within the same area) behavioural separation (different behaviours) ie: soil ph - ecological ie: different feeding patterns - behavioural
70
are mutations important factor in allopatric and sympatric speciation?
yes because w/o there wouldn't be new alleles of genes for selection
71
define artificial selection?
process by which humans choose organisms with desired traits and selectively breed them to enhance expression known as selective breeding
72
within selective breeding what is selected phenotype or genotype?
phenotype has a negative affected because breeder not worries about genetics so may be linked affecting organisms health
73
what is the process of selective breeding?
1. desired characteristics chosen and the two organisms shouldn't be closely related 2. bred together 3. offspring tested for desired traits 4. those that display desired trait are then selected for further breeding 5. continues for many generations
74
name some characteristics animals may be chosen to have when selectively bred?
higher yield of milk / meat chicken that lay larger eggs domestic dogs with gentle nature
75
within selective breeding why is it important to maintain a resource of genetic material?
needs to include genetic material close to original wild type ensures gene pool for particular species doesn't become too small
76
what negative affects does an inbreeding depression have?
increased chance of harmful recessive alleles combining decreased growth and survivability
77
within inbreeding are the animals closely linked? what does it lead too?
yes closely related to one another leads to reduction in gene pool so reduces number of alleles in a population = inbreeding depression leads to harmful genetic defects potentially

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